First, no matter how you set your sizer for a precision return your cases will springback differently by brand and number of times fired, annealed, etc. Meaning IF you only want to set the die precisely the same, that's quite easy to do with the lock ring. But IF you want to size your cases the same you will need to slightly change the die occasionally.

Next, fired cases have expanded and shrunk back a thou or two from full chamber length. Meaning there's absolutely no need to size shoulders further back from the fired length.